A Japanese Patent Application First Publication No. Heisei 11-96497 published on Apr. 9, 1999 exemplifies a previously proposed lane keep control apparatus. In the previously proposed lane keep control apparatus disclosed in the above-described Japanese Patent Application First Publication, when determining that the vehicle tends to be diverged from a traffic lane on which the vehicle is traveling, the previously proposed lane keep control apparatus prevents a divergence of the vehicle from the traffic lane by outputting a steering control torque having a magnitude against which the driver can easily overcome to a steering actuator according to a lateral deviation displacement of a traveling position of the vehicle with respect to a reference position of the traffic lane.